The physics behind the deadly 1919 Boston Molasses Flood
November 26, 2016 3:00 PM   Subscribe

On January 15, 1919, in Boston's North End, a 50-foot-tall tank holding 2.3 million gallons of molasses burst, unleashing a deadly wave that rose nearly 25 feet high at one point. The disaster killed 21 people and injured another 150. Nearly one hundred years later, an analysis carried out by a group of Harvard fluid dynamics physicists explains how "cold temperatures and unusual currents conspired to turn slow sticky goop into a deadly speeding wave."

Solving a Mystery Behind the Deadly ‘Tsunami of Molasses’ of 1919:

When the molasses arrived in Boston’s harbor, it was heated by just a few degrees. The warmer temperature made it less viscous and therefore easier to transport to a storage tank near the waterfront.

When the tank burst two days later, the molasses was still probably about four or five degrees Celsius warmer than the surrounding air, said Nicole Sharp, an aerospace engineer and science communications expert who advised the Harvard students. (She runs the website FYFD, through which she explains the principals of fluid dynamics to people outside academia.)


CBC interview with Nicole Sharp:

According to historical accounts, the molasses moved at a speed of 35 miles per hour, which is about 15.5 metres per second, which is really quite fast. Initially, I actually thought, "How in the world could it really have moved that fast?" and sort of surprised myself when I started doing the calculations. I realized that because the molasses is one and a half times denser than water and there was so much of it in this tank, in fact, fluid dynamics and the physics equations predict that it would move at speeds that are about 15 to 17 metres per second. It's totally in line with what the historical record says.
posted by mandolin conspiracy (23 comments total) 29 users marked this as a favorite
 




And ever since the molasses tide we've had to take off our shoes and turn on our laptop computers before we can get pancakes for breakfast.
posted by Bringer Tom at 4:06 PM on November 26, 2016 [2 favorites]




They mentioned that molasses is a shear-thinning fluid (it flows more easily the faster it deforms), though the effect is small. Can you imagine the positive feedback loop if you managed to spill some stubstance where the effect is significant? Non-newtonian fluid are weird.
posted by indubitable at 4:54 PM on November 26, 2016 [1 favorite]


Well, first of all, no one ever asks why we needed so much molasses to begin with. Seriously, I've never bought a bottle in my life but I see it is an ingredient in Boston baked beans so maybe that explains it.

Also this caption: "Fire House no. 31, damaged in the Molasses Disaster" is a masterful understatement. The building was knocked off its foundations.
posted by TWinbrook8 at 6:12 PM on November 26, 2016 [1 favorite]


Well, first of all, no one ever asks why we needed so much molasses to begin with.

Rum, mostly. In this case though, I believe the company to whom the molasses belonged was an industrial ethanol distiller.
posted by [expletive deleted] at 6:33 PM on November 26, 2016 [5 favorites]


Well, first of all, no one ever asks why we needed so much molasses to begin with.

It wasn't the molasses itself so much as the rum and distilled alcohol you could make from it. Before Prohibition, Boston was a major rum producer (going back to the Triangular Trade). During WWI, many of the tanks and distilleries were converted to produce pure alcohol for the war effort.
posted by adamg at 7:04 PM on November 26, 2016 [2 favorites]


It was an industrial tank, and initially the company responsible claimed it was terrorism, a bombing by anti-war immigrant anarchists. A corporate whistleblower who had repeatedly warned management that the tank was substandard came forward, in the end.

Really amazing (and tragic) story through-and-through.
posted by nev at 7:17 PM on November 26, 2016 [4 favorites]


Molasses is an industrial precursor to uncountable human food and animal feed products. I have been in molasses production facilities that make the one that collapsed in 1919 look a school kid's science fair project.
posted by Bringer Tom at 7:24 PM on November 26, 2016 [5 favorites]


So in other words: If you take the molasses out of the fridge and let it warm up, it will exit the bottle at faster rate. Hell, this means if you left a five gallon plastic jug of it hanging from a tree limb and shot it near the bottom from a safe distance it might even squirt a few feet and bleed out quick. This is also why the molasses tanker truck drivers who serve Death Valley...oh nevermind.

Next scientists will tell us that dogs have memories. Get a job, dorks.
posted by Mr. Yuck at 7:31 PM on November 26, 2016


My mom was born in 1930 in Boston and grew up in Littleton. While I was growing up one of the things she would say when I was moving slowly was "You're moving more slowly then molasses in January!" I didn't learn of this event until recently and I really wish I could of asked her about that phrase and how it related.
posted by lester at 7:36 PM on November 26, 2016 [1 favorite]


The Boston Public Library has some photos of the destruction, along with some newspaper front pages about the disaster.
posted by adamg at 7:45 PM on November 26, 2016 [2 favorites]


Molasses is an industrial precursor to uncountable human food and animal feed products.

This. Put it on grain and it's basically horse gasoline.
posted by sexyrobot at 7:51 PM on November 26, 2016 [12 favorites]


Preaching to the choir here but how many corporate and industrial regulations could a "pro business" POTUS clear out for the benefit of increased profits?

(I've been told that on a hot still day one can still smell the slightest molasses aroma on a certain street in the North End)
posted by sammyo at 8:31 PM on November 26, 2016


The Boston Public Library has some photos of the destruction, along with some newspaper front pages about the disaster.

Oh, wow. Thanks for that!
posted by mandolin conspiracy at 8:41 PM on November 26, 2016


Well, first of all, no one ever asks why we needed so much molasses to begin with

I spent the last year giving tours of the North End and talking in detail about this event. As fun as it is to talk about rum, the molasses industry had as much to do with munitions as it did with inebriation. Molasses ethanol was a key ingredient in the weapons manufacturing of WWI, and it was in high demand. War materiel. That, not rum or sweetener, was why we had massive stockpiles of sugary fuel sitting around.

It's also an excellent story to illustrate industrial negligence and the need for both industrial zoning (to get dangerous manufacturing out of residential areas) and regulation (to prevent things like the fact that this tank was supposed to be inspected regularly and was not, and that its flaws were hidden).

(I've been told that on a hot still day one can still smell the slightest molasses aroma on a certain street in the North End)

Not really any more (I've toured on plenty of insufferably hot days) but people did say this about the 1930s-40s.
posted by Miko at 9:07 PM on November 26, 2016 [12 favorites]


[after reading the links] "Flood" is the wrong word to characterize this event. "Spill" or "tsunami" would more accurately convey the devastating but localized effect of a wave of liquid laying waste to a specific area. And it was heinous not only because its force took out things like elevated railway supports, but because the people, dogs and horses trapped in the liquid couldn't just swim their way out; they were trapped in a sticky, viscous goo that impeded their efforts to struggle free. Horrifying.
posted by Miko at 9:16 PM on November 26, 2016 [2 favorites]


I have been in molasses production facilities that make the one that collapsed in 1919 look a school kid's science fair project.

I want to know every detail about giant molasses factories, please.
posted by Literaryhero at 12:09 AM on November 27, 2016 [4 favorites]


Catalogue these facts, Charles L. Hurlburt.

Oh, thank GOD. I was desperately trying to find this page last night, because it's not the kind of thing you can just describe without sounding like a madman.

Mrs. Example and I will still occasionally yell "CHARLES L. HURLBURT!" at each other in remembering-something-years-later situations.
posted by Mr. Bad Example at 5:28 AM on November 27, 2016 [1 favorite]


I want to know every detail about giant molasses factories, please.

About 50 miles from me is the largest sugar refinery in North America; they melt 7 to 9 million pounds of raw sugar per day to make both industrial and consumer products. Including a fairly large facility for holding and packing molasses in drums and rail cars. The scale on which they weigh what they receive raw sugar from barges is a 50,000 pound capacity hopper, and when they are unloading a barge it cycles about every 40 seconds.

A bit upriver from there is a transfer station which mostly takes rail shipments and stores them until they can be loaded onto ships. They have tanks about the size of the one that collapsed in 1919 -- over 50 of them on one site. Much of the product they handle isn't considered human food grade; it is destined for animal feed or industrial chemical processes.
posted by Bringer Tom at 7:11 AM on November 27, 2016 [4 favorites]


#6 on the list of Worst Ways to Die, Ever. Right behind cave diving accident and before explosive decompression.
posted by gottabefunky at 9:12 AM on November 27, 2016


Molasses ethanol was a key ingredient in the weapons manufacturing of WWI, and it was in high demand. War materiel. That, not rum or sweetener, was why we had massive stockpiles of sugary fuel sitting around.

Interesting. A distant uncle of mine had a munition's factory of some kind that went bust after the first war. I'm wondering what the financial status of this molasses thing would have been in 1919. Especially given that, come 1920, the stuff would be useless for making rum.

My father as a young person witnessed the aftermath of a happier food related industrial accident. Fire at a popcorn warehouse.
posted by BWA at 12:02 PM on November 27, 2016 [1 favorite]


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